1. Field of the Invention
The present invention relates to a driving machine driven by compressed air, flammable gas, an electric motor, or the like, and in particular to a driving machine which drives a fastener member into a member to be driven by turning-ON of a trigger after a push lever comes in contact with the member to be driven.
2. Description of the Related Art
There are driving machines utilizing compressed air, flammable gas, an electric motor or the like as a power source. Here, a driving machine utilizing flammable gas as a power source will be explained.
An action for driving a nail which is a fastener member will first be explained. A driving machine of this type includes a fuel canister therein to jet fuel from the fuel canister into a combustion chamber, thereby producing mixed gas. The combustion chamber is connected to a cylindrical cylinder and a piston movable in a vertical direction is accommodated in the cylinder. A push lever is pressed on a member to be driven and the trigger is pulled so that an spark plug ignites fuel. Gas in the combustion chamber combusts and a volume of mixed gas expands so that the piston is pressed downward. The piston is formed integrally with a rod-shaped driver blade and it is configured so as to drive a nail into a member to be driven such a wood.
Next, a structure of a switch will be explained. For safety, a portable type driving machine which does not include an external drive source such as a compressor adopts such a configuration that, after a push lever provided near a shooting port through which a nail is shot is brought in contact with a member to be driven to be pressed on the member to be driven, the trigger is pulled to start driving action. Such a switch structure is adopted that, unless the series of actions described above are performed, driving action is not performed. For example, such a configuration is adopted that, when the push lever is brought in contact with the member to be drive to be pressed thereon after the trigger is pulled, the driving machine cannot drive a nail into the member to be driven.
The driving machine of this type has a push switch which turns ON or OFF according to action of the push lever and a trigger switch which turns ON or OFF according to action of the trigger. The driving machine adopts such a configuration that, after the push switch turns ON, namely, unless the push lever is pressed on a member to be driven to be raised, the trigger switch does not turn ON. The driving machine with such a configuration is provided with a mechanism where, when the push lever is raised, the trigger switch turns ON together with a mechanism where, unless the push lever is raised, the trigger cannot be operated. Therefore, there is such a problem that the structure of the switch mechanism portion becomes complicated, which results in growth in size. Incidentally, Unexamined Japanese Patent Application KOKAI Publication No. 2006-224271 discloses a driving machine provided with a stopper member operating simultaneously with a trigger for preventing a combustion chamber frame from returning back to an initial position when a push lever is pressed so that a combustion chamber is formed.
There is also a driving machine where the abovementioned both switches are connected to a microcomputer accommodated in a housing. With this configuration, when the push lever is brought in contact with a member to be driven to be pressed on the same, a push switch turns ON via a link mechanism operating simultaneously with action of the push lever. The microcomputer senses such a fact that the push switch is in ON state by an electric signal. The microcomputer is programmed such that, when the trigger is then pulled so that the trigger switch turns ON, spark is generated at an spark plug. The driving machine adopts an electrical switch mechanism where the microcomputer is used. Since the switch mechanism requires the microcomputer, manufacturing cost is increased. Since the driving machine is frequently used outdoor, such a problem arises that the driving machine malfunctions due to noises generated by thunder or the driving machine is disabled by exposure to rain.